1. Field of the Invention
The present invention relates generally to methods and kits for making provisional and long-term dental crowns, bridges, inlays, onlays, veneers, implants, and other dental restorations. A shell or restoration form made of polymerizable material having good dimensional shape-stability is used to make the dental restoration. In one method, the restoration can be fabricated indirectly by a dental laboratory and sent to a dentist for placing in the mouth of a patient. In another version, the dentist can make the restoration in the dental office directly.
2. Brief Description of the Related Art
Dental restorations, such as crowns and bridges, are used to restore or replace lost tooth structure, teeth, or oral tissue. Provisional (or temporary) restorations are intended to be used for a relatively short time. For example, a dentist will often use a provisional crown, until a permanent crown is ready to be placed in the mouth of a patient. Following one conventional procedure, the dentist makes the provisional crown for the patient at the dental office and a dental laboratory makes the permanent crown. The dentist mounts the provisional crown to protect the tooth while the permanent crown is being made. Later, the dentist removes the provisional crown and replaces it with the permanent crown.
In one conventional method, the provisional crown is made using a prefabricated shell made of a metal such as aluminum, stainless steel, anodized gold, or polycarbonate. Because human teeth come in different sizes and shapes, many different shell forms must be available. The shell may be trimmed and shaped to fit properly over the prepared tooth structure. The shell cavity is typically filled with a polymerizable resinous material that may contain filler particulate. The shell containing the resinous material along with a temporary adhesive or cement is placed on the prepared tooth. The shell is irradiated with ultraviolet or visible light to cure the polymerizable resinous material and dental cement. Thus, the provisional crown is affixed to the tooth structure. Ideally, the shell form is shaped to achieve optimum margins, interproximal contacts, and occlusion. However, one problem with using prefabricated metal shell restorations is that they can be difficult to grind and shape. On the other hand, if polycarbonate shells are used, there can be problems with grinding the shell's occlusal surface—this may expose the filled resin and cause delamination and staining. Also, the bond strength between the shell and resin can be low even when a primer coating is used. Moreover, it is difficult to make adjustments to the rigid polycarbonate shell so as to obtain the desired bite surface. Another problem with using prefabricated metal shells is they may provide an esthetically non-pleasing appearance, and it can be difficult to find a shell that fits properly. One attempt to solve this problem involves providing many different shell forms having different sizes and shapes (for example, shells for molars and bicuspids). However, making so many different shell forms available to the dentist is expensive and time-consuming. As described further below, the polymerizable shell forms of this invention solve many of the problems associated with using conventional shell forms.
In recent years, techniques for making provisional crowns using prefabricated shells made of polymeric materials have been developed. For example, Rosellini, U.S. Pat. Nos. 5,192,207 and 5,332,390 disclose a method for making a permanent crown. After the tooth that will receive the crown has been prepared, a transparent shell tooth form is filled with a light-setting resin. The filled shell is placed on the prepared tooth and a light source (typically ultraviolet) is directed at thereon. This sets the light-setting resin and bonds the resin to the shell form. Preferably, the shell form is made from the same light-setting resin used to fill the shell so that there is good bonding therebetween. Thereafter, the tooth form is shaped and polished in situ to form the permanent crown.
Updyke, U.S. Pat. No. 5,775,913 discloses a method that allows a dentist to “cap” a tooth in a single office visit. The preferred material for making the crown shell or cap is known as ARTGLASS (Herarus Kulzer), a photopolymerizable multifunctional methacrylate monomer resin filled with different sized glass particles. The shell is prepared by molding and light-curing the ARTGLASS material. Then the cap is filled with an uncured, resinous material, preferably CHARISMA (Herarus Kulzer), a photopolymerizable multifunctional methacrylate monomer resin filled with glass particles. The cap is placed over the prepared tooth and the patient bites down. The dentist uses a curing light to cure the interior resin so that it bonds with the tooth and becomes integral with the cap.
Harlan, U.S. Pat. No. 6,935,862 discloses a method for making a crown, short-span bridge, or other dental prosthesis in a single office visit. The method involves placing a prefabricated shell that can be made from a polymerizable material, for example CRISTOBAL, a polyacrylic glass composite (Dentsply) over a prepared tooth. The shell is trimmed to achieve desired seating on the tooth and optimal occlusion. The shell is then removed from the tooth, and the tooth's prepared surface is painted with a separating medium. An interior surface of the shell is painted with a bonding agent, and an uncured composite material is added to the shell's cavity. Next the shell is positioned over the tooth, and the composite material in the cavity of the shell is partially light cured in situ. The shell is removed from the tooth and uncured composite material is added to the external surface of the shell. The added composite is then fully light cured, and the shell is affixed to the tooth.
Kvitrud et al., US Patent Application Publication US 2005/0042577 discloses dental crown forms having a handle attached to the crown form at a location removed from the base of the crown form. The crown form is filled with a hardenable material shortly before placing the crown form over the prepared tooth. The handle can be vented so that excess material can pass during placement of the crown form. One advantage with this crown form according to the published application is that the handle provides improved accessibility during placement of the crown form on the tooth. The published application notes that if the hardenable dental material is of a type that can retain its desired shape before hardening and after release from the interior surfaces of the dental crown form, the practitioner may remove the dental crown form before hardening the dental material.
In another instance, Chilibeck, U.S. Pat. No. 6,884,073 discloses a method for making temporary and semi-permanent crowns using a crown shell or form that is filled with resin. The crown form and resin are made from photopolymerizable materials, preferably comprising Bis-GMA. The crown form, having an incompletely polymerized layer is filled with resin. The crown is then fitted onto the tooth stub. The incompletely polymerized layer of the crown and injected resin are photopolymerized or autopolymerized in the mouth of the patient. The incompletely polymerized layer polymerizes with the resin as the resin is being polymerized.
As discussed above, there are numerous methods for making conventional provisional (temporary) dental restorations such as crowns and short-span bridges. A patient wears the provisional crown for a relatively short period of time, that is, until a permanent crown is made. Today, provisional crowns and bridges typically are used by a patient for a period of about three to six months. In general, such provisional restorations are effective, but there is a need in the dental field for restorations that can be used for longer periods. One object of the present invention is to provide dental restorations that can be used short-term (for example, a period of about one to twelve months) and long-term (for example, greater than twelve months).
The present invention provides methods for making such dental restorations using shell forms. A dental practitioner can use the resulting dental restoration as a provisional expecting that it will remain in the patient's mouth for a time period of about 1 to about 12 months. On the other hand, if the dental practitioner wishes to use the dental restoration as a long-term product, expecting that it will remain in the patient's mouth for a period of time longer than about 12 months, he or she can do so. The dental restorations of this invention can be used as either provisional or long-term dental products because of their advantageous properties. Particularly, the restorations are strong and durable and do not break or fracture easily. Because of their mechanical strength, the restorations can withstand hard occlusion forces. In addition, the restorations have pleasing aesthetics matching the shade of natural teeth. Moreover, the restorations have good margins and contacts, providing the patient with comfort while promoting dental health. The restoration covers and supports the tooth structure sufficiently so that it protects the tooth's pulpal portion.
Another object of the present invention is to provide a method that a dental laboratory can use to easily make dental crowns, bridges, inlays, onlays, veneers, implants, and other dental restorations having good mechanical strength, aesthetics, and occlusal fit.
Another object of this invention is to provide a method that a dental practitioner can easily use to design and fabricate the crown, bridge, or other dental restoration “chairside.” This would help make the crown manufacturing and fitting process less time-consuming and costly. The dentist would be able to prepare and mount the crown on the patient's tooth in a single office visit. In such a method, the dentist should be able to check the crown and easily make adjustments, if needed, to achieve optimum comfort and fit. Another object of this invention is to provide a material which can be shaped and contoured easily to prepare a crown having good comfort and fit.
These and other objects, features, and advantages of this invention are evident from the following description and illustrated embodiments.